1. Field of the Invention
The present invention relates to testing of integrated circuit devices. More particularly, the present invention is directed to a control system and a control method for controlling test procedures by processing test data generated from the test procedures and analyzing the test data.
2. Background of the Related Art
In general, semiconductor IC devices are fabricated via hundreds of processing steps, and must be subjected to a variety of test processes to verify their electrical function, performance, and reliability prior to shipment. The test processes include, among others, a final test and a quality assurance (QA) test. In the final test, all of the IC devices that have passed through the wafer fabrication steps and assembly processing steps are tested and sorted into good or failed devices. The final test may be performed on a number of identical IC devices manufactured under the same processing environment, for example, up to two thousand devices at once.
According to the results of the final test, the IC devices are classified in certain bin categories. For example, IC devices classified as BIN 1 (i.e., bin category 1), have experienced no failures and are thus regarded as good or passed devices, while IC devices classified as BIN 7 (i.e., bin category 7) are regarded as defective devices with the main cause of failure being excessive leakage current. Of course, any number of bin categories and bin numbering systems may be employed depending on the semiconductor manufacturer and the nature of the IC devices to be tested. For example, other bin categories could accommodate failures due voltage or current being outside an acceptable range, open/short failures, or differing memory access times.
The QA test is used to confirm the results of the final test and to assure the quality of the devices requested by specific customers by testing predetermined numbers of devices sampled from the good devices (e.g., BIN 1 devices) that have passed the final test. After passing the QA test, the good devices are delivered to the customers.
Present day semiconductor markets call for multiple species of small quantity, high technology and short life cycle devices. Due to the short life cycle and specialized nature of the devices, manufacturers who develop and sell new IC devices require the ability to quickly set-up the production lines, as well as have fast, accurate analysis of the causes of failures so as quickly correct defects in the production line. Furthermore, the time required for testing should also be reduced as much as possible without sacrificing quality or reliability. To do so, the manufacturers need to control the overall test procedures and to integrally manipulate test data. In order to stabilize the product lines and produce high quality devices, failure analysis and test data should be made readily available to the designers and production personnel so that changes may be reflected in circuit design, wafer fabrication, and assembly steps.